Question

A wave with low frequency would have relatively ________.

• A. high energy and a short wavelength
• B. high energy and a long wavelength
• C. low energy and a long wavelength
• D. low energy and a short wavelength

Answer 1

The correct option is C low energy and a long wavelength

The mathematical equation that relates the energy ($\text{E}$) of light to its frequency is-

$\text{E}=\text{h}\nu$
where, $\nu$ is frequency, $\text{h}$ is Planck's constant
$\text{h}$ = $6.626\times {10}^{-34}$

With the help of the above equation we can say that as the frequency of a wave increases, its energy also increases.

Also from the wave equation,
$\text{c}$ = $\lambda \nu$

where, c = speed of light = $3\times$${10}^8$ m/s
$\lambda$ = wavelength
$\nu$ = frequency

Rearranging the equation,
$\nu$ = $\text{c}$/$\lambda$

So, we can say from this equation that as the frequency of a wave decreases, its wavelength increases and vice versa.

In other words, the energy of light is directly proportional to its frequency and inversely proportional to its wavelength.